Thoracic duct lymph chylomicrons, doubly labeled in vivo with (1-3H)retinol and (4-14C)cholesterol were administered intravenously to both normal and hypercholesterolemic foxhounds to determine to what extent cholesteryl ester rich chylomicron remnants contribute to the dietary-induced hypercholesterolemia in these animals. The rapid removal of chylomicrons from the circulation and the subsequent recovery of the radioactivity in the livers of these animals indicated that none of the large plasma pools of cholesterol (B-VLDL, LDL, or HDLc) represented chylomicron remnants accumulating in the plasma.